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	$181.65	11.265%	$202.1129	$202.11	$202.10	$202.10
Purchase #2	$82.96	4.362%	$86.5787	$86.58	$86.60	$86.60
Purchase #3	$63.94	13.553%	$72.6058	$72.61	$72.60	$72.60
Purchase #4	$97.46	9.632%	$106.8473	$106.85	$106.85	$106.80
Purchase #5	$235.82	11.687%	$263.3803	$263.38	$263.40	$263.40
Purchase #6	$127.92	4.693%	$133.9233	$133.92	$133.90	$133.90
Purchase #7	$176.92	6.347%	$188.1491	$188.15	$188.15	$188.10
7 purchase totals =	$966.67		$1,053.5974	$1,053.60	$1,053.60	$1,053.50