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	$176.83	13.796%	$201.2255	$201.23	$201.25	$201.20
Purchase #2	$31.85	4.796%	$33.3775	$33.38	$33.40	$33.40
Purchase #3	$38.66	9.784%	$42.4425	$42.44	$42.45	$42.40
Purchase #4	$153.96	3.668%	$159.6073	$159.61	$159.60	$159.60
Purchase #5	$76.66	11.552%	$85.5158	$85.52	$85.50	$85.50
Purchase #6	$72.70	5.824%	$76.934	$76.93	$76.95	$76.90
Purchase #7	$141.85	3.738%	$147.1524	$147.15	$147.15	$147.20
7 purchase totals =	$692.51		$746.2550	$746.26	$746.30	$746.20