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	$191.66	11.596%	$213.8849	$213.88	$213.90	$213.90
Purchase #2	$164.41	4.462%	$171.746	$171.75	$171.75	$171.70
Purchase #3	$89.87	9.181%	$98.121	$98.12	$98.10	$98.10
Purchase #4	$44.61	9.566%	$48.8774	$48.88	$48.90	$48.90
Purchase #5	$167.36	10.847%	$185.5135	$185.51	$185.50	$185.50
Purchase #6	$130.58	4.530%	$136.4953	$136.50	$136.50	$136.50
Purchase #7	$161.71	6.362%	$171.998	$172.00	$172.00	$172.00
7 purchase totals =	$950.20		$1,026.6361	$1,026.64	$1,026.65	$1,026.60