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	$48.30	7.559%	$51.951	$51.95	$51.95	$52.00
Purchase #2	$100.76	4.240%	$105.0322	$105.03	$105.05	$105.00
Purchase #3	$17.79	13.707%	$20.2285	$20.23	$20.25	$20.20
Purchase #4	$30.29	8.652%	$32.9107	$32.91	$32.90	$32.90
Purchase #5	$85.98	12.375%	$96.62	$96.62	$96.60	$96.60
Purchase #6	$64.33	8.625%	$69.8785	$69.88	$69.90	$69.90
Purchase #7	$99.59	9.556%	$109.1068	$109.11	$109.10	$109.10
7 purchase totals =	$447.04		$485.7277	$485.73	$485.75	$485.70