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	$193.82	3.689%	$200.97	$200.97	$200.95	$201.00
Purchase #2	$205.79	3.145%	$212.2621	$212.26	$212.25	$212.30
Purchase #3	$167.26	6.590%	$178.2824	$178.28	$178.30	$178.30
Purchase #4	$226.52	6.353%	$240.9108	$240.91	$240.90	$240.90
Purchase #5	$48.73	11.647%	$54.4056	$54.41	$54.40	$54.40
Purchase #6	$86.42	3.451%	$89.4024	$89.40	$89.40	$89.40
Purchase #7	$135.48	11.700%	$151.3312	$151.33	$151.35	$151.30
7 purchase totals =	$1,064.02		$1,127.5645	$1,127.56	$1,127.55	$1,127.60