Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$173.67	13.359%	$196.8706	$196.87	$196.85	$196.90
Purchase #2	$209.90	6.452%	$223.4427	$223.44	$223.45	$223.40
Purchase #3	$176.94	11.299%	$196.9325	$196.93	$196.95	$196.90
Purchase #4	$217.40	5.569%	$229.507	$229.51	$229.50	$229.50
Purchase #5	$53.41	8.294%	$57.8398	$57.84	$57.85	$57.80
Purchase #6	$222.91	5.118%	$234.3185	$234.32	$234.30	$234.30
Purchase #7	$170.63	12.474%	$191.9144	$191.91	$191.90	$191.90
7 purchase totals =	$1,224.86		$1,330.8255	$1,330.82	$1,330.80	$1,330.70