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	$205.40	3.444%	$212.474	$212.47	$212.45	$212.50
Purchase #2	$85.66	9.347%	$93.6666	$93.67	$93.65	$93.70
Purchase #3	$232.89	3.388%	$240.7803	$240.78	$240.80	$240.80
Purchase #4	$143.45	5.793%	$151.7601	$151.76	$151.75	$151.80
Purchase #5	$101.65	9.576%	$111.384	$111.38	$111.40	$111.40
Purchase #6	$150.40	13.119%	$170.131	$170.13	$170.15	$170.10
Purchase #7	$181.82	4.796%	$190.5401	$190.54	$190.55	$190.50
7 purchase totals =	$1,101.27		$1,170.7361	$1,170.73	$1,170.75	$1,170.80