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	$201.61	10.277%	$222.3295	$222.33	$222.35	$222.30
Purchase #2	$6.33	5.244%	$6.6619	$6.66	$6.65	$6.70
Purchase #3	$104.33	6.311%	$110.9143	$110.91	$110.90	$110.90
Purchase #4	$60.62	11.501%	$67.5919	$67.59	$67.60	$67.60
Purchase #5	$229.46	11.205%	$255.171	$255.17	$255.15	$255.20
Purchase #6	$242.84	10.197%	$267.6024	$267.60	$267.60	$267.60
Purchase #7	$165.63	3.544%	$171.4999	$171.50	$171.50	$171.50
7 purchase totals =	$1,010.82		$1,101.7709	$1,101.76	$1,101.75	$1,101.80