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	$85.47	4.478%	$89.2973	$89.30	$89.30	$89.30
Purchase #2	$219.96	7.169%	$235.7289	$235.73	$235.75	$235.70
Purchase #3	$8.53	3.627%	$8.8394	$8.84	$8.85	$8.80
Purchase #4	$242.95	4.616%	$254.1646	$254.16	$254.15	$254.20
Purchase #5	$162.45	11.432%	$181.0213	$181.02	$181.00	$181.00
Purchase #6	$188.77	11.650%	$210.7617	$210.76	$210.75	$210.80
Purchase #7	$53.59	3.482%	$55.456	$55.46	$55.45	$55.50
7 purchase totals =	$961.72		$1,035.2692	$1,035.27	$1,035.25	$1,035.30