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	$181.90	7.181%	$194.9622	$194.96	$194.95	$195.00
Purchase #2	$102.48	7.621%	$110.29	$110.29	$110.30	$110.30
Purchase #3	$244.51	9.811%	$268.4989	$268.50	$268.50	$268.50
Purchase #4	$196.34	13.772%	$223.3799	$223.38	$223.40	$223.40
Purchase #5	$241.67	5.576%	$255.1455	$255.15	$255.15	$255.10
Purchase #6	$250.90	7.495%	$269.705	$269.71	$269.70	$269.70
Purchase #7	$19.71	10.777%	$21.8341	$21.83	$21.85	$21.80
7 purchase totals =	$1,237.51		$1,343.8156	$1,343.82	$1,343.85	$1,343.80