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	$168.38	7.687%	$181.3234	$181.32	$181.30	$181.30
Purchase #2	$119.51	6.248%	$126.977	$126.98	$127.00	$127.00
Purchase #3	$11.36	9.731%	$12.4654	$12.47	$12.45	$12.50
Purchase #4	$152.30	11.167%	$169.3073	$169.31	$169.30	$169.30
Purchase #5	$242.45	10.799%	$268.6322	$268.63	$268.65	$268.60
Purchase #6	$127.62	4.822%	$133.7738	$133.77	$133.75	$133.80
Purchase #7	$228.94	9.578%	$250.8679	$250.87	$250.85	$250.90
7 purchase totals =	$1,050.56		$1,143.3470	$1,143.35	$1,143.30	$1,143.40