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	$164.33	13.741%	$186.9106	$186.91	$186.90	$186.90
Purchase #2	$235.73	7.502%	$253.4145	$253.41	$253.40	$253.40
Purchase #3	$88.26	7.436%	$94.823	$94.82	$94.80	$94.80
Purchase #4	$78.94	12.581%	$88.8714	$88.87	$88.85	$88.90
Purchase #5	$35.69	11.113%	$39.6562	$39.66	$39.65	$39.70
Purchase #6	$89.52	11.484%	$99.8005	$99.80	$99.80	$99.80
Purchase #7	$188.33	9.264%	$205.7769	$205.78	$205.80	$205.80
7 purchase totals =	$880.80		$969.2531	$969.25	$969.20	$969.30