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	$154.27	4.653%	$161.4482	$161.45	$161.45	$161.40
Purchase #2	$35.53	4.585%	$37.1591	$37.16	$37.15	$37.20
Purchase #3	$65.54	3.534%	$67.8562	$67.86	$67.85	$67.90
Purchase #4	$62.39	7.801%	$67.257	$67.26	$67.25	$67.30
Purchase #5	$151.88	6.826%	$162.2473	$162.25	$162.25	$162.20
Purchase #6	$50.58	6.470%	$53.8525	$53.85	$53.85	$53.90
Purchase #7	$42.41	4.442%	$44.2939	$44.29	$44.30	$44.30
7 purchase totals =	$562.60		$594.1142	$594.12	$594.10	$594.20