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	$91.32	6.104%	$96.8942	$96.89	$96.90	$96.90
Purchase #2	$167.41	8.421%	$181.5076	$181.51	$181.50	$181.50
Purchase #3	$176.79	3.130%	$182.3235	$182.32	$182.30	$182.30
Purchase #4	$165.63	6.142%	$175.803	$175.80	$175.80	$175.80
Purchase #5	$38.26	11.244%	$42.562	$42.56	$42.55	$42.60
Purchase #6	$154.73	8.695%	$168.1838	$168.18	$168.20	$168.20
Purchase #7	$228.81	11.119%	$254.2514	$254.25	$254.25	$254.30
7 purchase totals =	$1,022.95		$1,101.5255	$1,101.51	$1,101.50	$1,101.60