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	$187.41	9.420%	$205.064	$205.06	$205.05	$205.10
Purchase #2	$171.75	7.154%	$184.037	$184.04	$184.05	$184.00
Purchase #3	$128.29	11.423%	$142.9446	$142.94	$142.95	$142.90
Purchase #4	$233.96	11.412%	$260.6595	$260.66	$260.65	$260.70
Purchase #5	$19.63	8.273%	$21.254	$21.25	$21.25	$21.30
Purchase #6	$110.59	5.650%	$116.8383	$116.84	$116.85	$116.80
Purchase #7	$64.89	11.530%	$72.3718	$72.37	$72.35	$72.40
7 purchase totals =	$916.52		$1,003.1692	$1,003.16	$1,003.15	$1,003.20